In recent years, vehicles are increasingly available that are mounted with navigation systems and the other systems that visualize various kinds of information. Generally, a liquid crystal display is used as the system's display screen and is disposed at a console and the like inside the vehicle.
However, a driver sometimes needs to visually recognize various kinds of information displayed on the display screen disposed as mentioned above while the vehicle is running. In such case, the driver must move his or her sight line to the display screen inside the vehicle from a road, signs, and the like forward outside the vehicle. This poses a problem of reducing the attention in front of the vehicle.
To solve this problem, a vehicle information display system using a so-called head up display (HUD) is known (e.g., see Patent Document 1). This technology reflects an image indicating various kinds of information on the vehicle's windshield and allows a vehicle's occupant to visually recognize the image as a virtual image so as to decrease the movement of the occupant's sight line for visually recognizing the displayed information.
Such vehicle information display system using the HUD may provide a driver with various kinds of information in the future. In such case, there is a problem of hiding important information needed for the current driving operations and the like behind the other much information and preventing the driver from promptly recognizing the important information. Another problem is possibility of hindering the driver's visual field depending on display positions of the image (information).
Some vehicle information display system using the HUD displays various kinds of information (videos) provided for a driver at a windshield's bottom part so as not to obstacle the driver's visual field to confirm traffic circumstances (e.g., see Patent Document 2). The windshield's bottom part is also referred to as a “bottom area” hereafter.
Here, the HUD can safely provide necessary information without making the driver's sight line move greatly. The HUD can provide all types of information in the future. However, only a limited size is ensured for the windshield's bottom area to display the information. It is impossible to display much information at a time.
When the display area is enlarged to display more information, the visual field area decreases to hinder the driver's visual field, making the driver uneasy.
Conventionally, a driver driving a vehicle may need to look at a guide signboard installed near a road in order to obtain route guide information and road information.
However, the driver may not be able to obtain sufficient information by looking at guide signboards near the road. For example, guide signboards on the road may not be easily identifiable. Alternatively, the driver may lose timing to look at the signboards. It is very dangerous for the driver to continue driving though he or she is not provided with sufficient information and therefore feels uneasiness and stress. As a result, the driver may fail to identify surrounding vehicles and signs. For example, the driver may fail to notice a passerby rushing out on the road or a temporary stop at the intersection with no traffic lights.
To decrease the above problem, route guide information and road information can be additionally obtained by using a navigation system. Further, in the above-mentioned Patent Document 1, the navigation system has a method of displaying the route guide information using arrows and letters on a vehicle's windshield and providing a driver with the route guide information superimposed on the actual road. This decreases a burden for the driver to drive a vehicle by comparing the actual road with a road on the display to thereby forcibly move his or her sight line and make him or her err in his or her judgment to take the wrong road.
However, according to the above-mentioned method described in Patent Document 1, the display on the route guide information may overlap with a sight of a preceding vehicle. In such case, the driver may feel uncomfortably to cause trouble with the driving. This may expose the driver to danger. Further, when the windshield shows the arrows and letters that are quite different from the real world, the driver may also feel uncomfortably to cause trouble with the driving.
A vehicle display apparatus uses a head-up display (HUD) that reflects an image from a display device on a windshield in front of a driver and enlarges the image, providing an advantage of improved visibility (see Patent Document 3).
Another vehicle display apparatus is proposed to provide a liquid crystal display device instead of the HUD by dividing the display into top and bottom sections. That is to say, the liquid crystal display device is mounted except the windshield's center area that may obstruct the driver's view (see Patent document 4).
On the other hand, the vehicle display apparatus using the HUD as disclosed in Patent Document 3 displays information about the vehicle on the driving visual field area in front of the driver. In this case, a driver's visual field is hindered during driving. In contrast, the information may be displayed only on the bottom area of the windshield except the driving visual field area. However, in this case, it is impossible to notify the driver of much information.
The vehicle display apparatus as disclosed in Patent Document 4 divides the liquid crystal display device into top and bottom sections and mounts them on the windshield. It is possible to notify the driver of much information without annoying him or her. Since the vehicle display apparatus is not an HUD, however, the information cannot be enlarged for display. As a result, it is necessary to form a large or a plurality of liquid crystal display apparatuses on the windshield, increasing manufacturing costs of the vehicle display apparatus.
(Patent Document)
Patent Document 1: JP 2001-108476 A
Patent Document 2: JP 2002-19491 A
Patent Document 3: JP S57-148530 U (Utility patent, Jitsuyo-shinan)
Patent Document 4: JP H11-15420 A